Evaluation of Weather Conditions for Methyl Bromide Ambient Air Monitoring in Monterey, Santa Cruz, and Kern Counties in the Year 2000
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Abstract:
Weather condition is one of the most important factors affecting spatial and temporal distributions of air pollutants, especially for short-term air dispersion. Abnormal weather conditions might lead to higher or lower ambient air concentrations than they would be under normal weather conditions. Therefore, testing for normality of weather conditions during the air monitoring period is an essential step for evaluating ambient air monitoring results. In this paper, a distance method was used to select a most representative weather station from the available candidates. An array of meteorological elements were identified that affect air dispersion and transportation. A statistical method was used to determine whether the weather conditions during the air monitoring period were significantly different from that of previous years. Using methyl bromide ambient air monitoring as a case study, this paper documents the methods, procedures, and results of weather analysis for Monterey, Santa Cruz, and Kern Counties during ambient air monitoring periods for methyl bromide in the year 2000. With a few exceptions, the meteorological elements and atmospheric stability factors, such as wind speeds, wind directions, and stability classes, during the monitoring period were in the normal range. Although there were higher frequencies of stable atmospheric conditions in Monterey/Santa Cruz Counties than in Kern County, weather conditions during the monitoring period were not significantly different from normal local weather conditions of previous years. Consequently, the subchronic air concentrations observed during the ambient air monitoring periods for methyl bromide in the year 2000 was taken under typical weather conditions of those areas at that time of the year.Keywords:
Air monitoring
Weather station
Atmospheric instability
The pilot balloon observation system with dual theodolite was used to investigate the effect of near-surface wind characteristics on pollutant diffusion in Yuxi NO.1 middle school, and by using the meteorological observation data analysis of the different weather characteristic and the impact on the pollutant concentration distribution. The experimental results showed that the predominant wind direction was not so apparent due to the affection of channels to the wind and the valley of the wind. During the observation, the regional atmospheric stability is more unstable and neutral stability, and longer duration of neutral stability would not be good at contamination diffusion. Winds profile observed four types of irregular, reverse, extreme value, normal. Under neutral stability conditions, the degree of fitting of wind profile exponent P in normal-type wind velocity is good, and its value is 0.608. The mountain-valley wind relates to daily range of temperature and the greater this difference in temperature is, the more frequency of mountain-valley wind blowing. In the morning and evening is the transition of mountain-valley wind, the period of time due to wind direction changes, causing the circulate accumulation of the pollutants in the air over the city.
Atmospheric instability
Prevailing winds
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